In a conventional substrate processing apparatus, when a substrate is subjected to a plasma processing, the substrate is attracted and held on an electrostatic chuck by an electrostatic force. A focus ring is provided on the electrostatic chuck to surround a region where the substrate is mounted.
In the above substrate processing apparatus, when a plasma used for the plasma processing for the substrate is generated, a temperature of the focus ring is increased by the plasma. To that end, a heat transfer medium is supplied to a space formed between the focus ring and the electrostatic chuck to suppress the temperature increase. By supplying the heat transfer medium to the space formed between the focus ring and the electrostatic chuck, heat of the focus ring is transferred to the electrostatic chuck via the heat transfer medium.
If airtightness of the space formed between the focus ring and the electrostatic chuck is not ensured, the heat transfer medium supplied to the space leaks to the outside, which results in deterioration of the heat transfer between the focus ring and the electrostatic chuck. Therefore, it is preferable to ensure the airtightness between the focus ring and the electrostatic chuck.
Therefore, there is suggested a technique of attracting and holding a focus ring on an electrostatic chuck by applying a voltage to an electrode provided at a region in the electrostatic chuck which corresponds to the focus ring, see, e.g. Japanese Patent No. 4913313.
However, such a conventional technique has a problem that the amount of leakage of the heat transfer medium supplied to the space formed between the focus ring and the electrostatic chuck may increase.
In other words, in the above conventional technique, misalignment between the focus ring and the electrostatic chuck may occur because the focus ring is not attracted and held on the electrostatic chuck in a period other than a plasma processing period in which a plasma for processing the substrate is generated. If misalignment between the focus ring and the electrostatic chuck occurs, the airtightness of the space formed between the focus ring and the electrostatic chuck deteriorates, and thus, the heat transfer medium supplied to the space leaks to the outside. As a result, in the above conventional technique, the amount of leakage of the heat transfer medium supplied to the space formed between the focus ring and the electrostatic chuck may increase.